The present invention relates to the field of electronic test equipment, and mre particularly to the field of test jigs or specialized setup equipment employed in testing electronic components.
As is well-known in the field of electronic equipment manufacture, the process of correcting hidden flaws and optimizing a new design, collectively referred to as "debugging", often requires as much or more time and effort than does the original design and fabrication. This process usually requires access to electronic components mounted on printed circuit boards (PCBs) on a lead-by-lead basis, in order to test individual portions of the integrated circuits within the component. That process can be difficult, inasmuch as the components, and their multiple leads, are designed for maximum packing density, not for ease of access.
Solutions providing ready access to VLSI (very large scale integration) devices are normally very cumbersome. One approach, for example, is to solder a "pigtail" on each lead, allowing for easy attachment of test leads to any pin on the device. Clearly, however, when considering a device with up to 224 pins, the effort involved in such a method is tedious, time-consuming, expensive, and potentially hazardous to the device. Considering the number of such devices contained within an end item such as a minicomputer, wide resort to such methods simply could not succeed.
Alternatively, a clip fixture can be employed to make temporary connections to certain types of devices. A fixture is designed to make contact with the leads of a particular type of device, and the fixture physically attaches to the device, held in place by spring pressure. This method is limited to devices such as dual-in-line packages (DIPs) that are spaced from other components by a sufficient distance to allow the placement of the fixture over the device.
Another approach to this problem is the use of a "vacuum table", designed to allow connection to each pin location on a PCB. Such a device clamps onto a printed circuit board, typically by vacuum or mechanical means, and has a connection point for each pin location on the board, allowing technicians and engineers to gain access to each component on that board.
Such tools are obviously highly expensive to produce, however, as it must replicate the design of an entire PCB. Equally clearly, a new tool must be fabricated for each different (or redesigned) PCB. In addition, the great number of pin locations with which the tool must make contact necessitates a high degree of accuracy in positioning the tool relative to the PCB, generally requiring some sort of alignment means, such as locating pins or the like. Additionally, the positioning of such a large number of test probes in close proximity to the PCB introduces a high capacitance associated with such probes. With some circuit board designs, the added presence of such capacitance interferes with or prevents the proper operation of the PCB circuitry.
The net result has been that this problem has continued, with solutions being left to the improvisational talents of individual workers. That method has, of course, required the expenditure of large amounts of time and effort in attempting to arrive at a general solution. A widely-applicable technique has, however, evaded the art to date.